Field of the invention

The present invention relates to a method and a device for detecting microorganisms from fluid, such as water.

Background of the invention

The contamination of fluids, such as waters, by micro-organisms and the like is a significant problem which causes significant threat to public health. In order to monitor the presence of such micro-organisms in for example water generally conventional microbiological techniques are used. This may involve taking samples, growing the micro-organisms in specific media and finally detecting the microorganisms with specific methods. This is laborious and takes a lot of time. Therefore quick and simple methods are required. Such methods should be preferable applicable on-the-spot, i.e. complex laboratory analysis should be avoided.

Summary of the invention

An object of the invention is to alleviate and eliminate the problems relating to the known prior art. Especially the object of the invention is to provide a fast, easy and reliable measuring technique for detecting a presence of micro-organisms in a fluid.

The object of the invention can be achieved by the features of independent claims.

The invention relates to a method of claim 1 , as well as to a device of claim 9, arrangement of claim 15 and computer program product of claim 19.

In an embodiment of the present invention it was surprisingly discovered that when micro-organisms present in a fluid are degraded, it causes a change in optical properties, such as in the turbidity of the fluid, where the degree of change correlates to the amount of degraded micro-organisms. By detecting this change, preferably by detecting scattered or transmitted light from the fluid, the presence and amount of the micro-organisms can be defined. Still further it is surprisingly dis- covered that with added or pulsed disintegrating force, it is possible to estimate the quantity and in some cases the indication of quality of the micro-organism.

According to an embodiment of the present invention a method is provided for detecting micro-organisms from a fluid, wherein a disintegrating force is allocated to the fluid and a change in at least one optical property, such as turbidity, of the fluid is detected before and after or during the disintegration wherein the change in the optical property, such as turbidity, as the result of the disintegration of the microorganisms indicates the presence of the micro-organisms.

According to an embodiment of the present invention also a device for detecting micro-organisms from fluid is provided, wherein the device advantageously comprises means for allocating a disintegrating force to the fluid and means for detecting a change in at least one optical property, such as in turbidity, of the fluid before and after or during the disintegration wherein the change in the optical property, such as turbidity, as the result of the disintegration of the micro-organisms indi- cates the presence of the micro-organisms.

The present invention also provides a device for detecting micro-organisms from solid surface by washing the micro-organisms with liquid to the detector mentioned.

One advantage of the present invention is that the test can be carried out very quickly, even in a fraction of a minute. In addition the invention provides a laboratory free technique, i.e. time consuming analysis or experts are not needed to conduct the detection measurement.

Another advantage of the present invention is that only a small amount of fluid is needed. In some embodiments of the invention it is not necessary to take a sepa- rate sample but the test can be conducted in situ.

Still another advantage of the present invention is that no complex chemical or biological analysis are needed and the use of harmful reagents can be avoided.

Still another advantage of the present invention is using UV-LED's as disintegrating force, the instrument cost can be low.

Still another advantage of the present invention is that different know disintegrating forces can be used instead or in addition of UV radiation. Brief description of the drawings

Figure 1 is a flow diagram showing the basic steps of one embodiment of the invention.

Figure 2 shows an exemplary arrangement of the invention wherein the fluid flows in a channel and a UV light source, a visible light source and a light detector are positioned at specific locations.

Figure 3 shows another exemplary arrangement of the invention wherein the fluid flows in a channel and a UV light source, a pattern of visible light sources and a light detector are positioned at specific locations. Figure 4 shows an exemplary device of the invention for detecting microorganisms from fluid.

Figure 5 shows another exemplary measuring construction for detecting the presence of micro-organisms in the fluid according to an exemplary embodiment of the present invention.

Figure 6 shows an exemplary concentrator for concentrating possible microorganisms from the fluid before measurement according to an exemplary embodiment of the present invention.

Figure 7 shows an exemplary measuring arrangement having a reference chamber according to an exemplary embodiment of the present invention.

Figures 8A-C show an exemplary measuring arrangement for measuring a change of an optical property (turbidity, absorptivity) according to an exemplary embodiment of the present invention.

Figure 9 shows another exemplary measuring construction for measuring a change of an optical property according to an exemplary embodiment of the present invention.

Figure 10 shows an exemplary embodiment for calculating out effects of sample inhomogenity and dirt accumulation according to an exemplary embodiment of the present invention. Figure 11A shows an exemplary behavior of concentration of micro-organisms during the allocation of disintegrating force into the fluid including microorganisms.

Figure 11 B shows an exemplary measuring data of concentration of microorganisms during the allocation of disintegrating force into the fluid including micro-organisms.

Detailed description of the invention

The present invention provides a method for detecting micro-organisms from fluid. The micro-organisms, or microbes, as used herein include generally all bacteria, fungi, archaea, and protists, as well as some microscopic plants (called green algae) and animals such as plankton, the planahan and the amoeba. Also viruses are included. Most microorganisms are unicellular (or single-celled), but this is not universal, since some multicellular organisms are microscopic (Wikipedia). In one embodiment the micro-organisms are bacteria. Micro-organisms may include here e.g. viruses, if they are of such species that can be disintegrated by the used force.

The fluid as used herein includes all liquids which can be applied to the method of the invention, such as waters. Non-limiting examples of such fluids include tap wa- ter, natural waters, washing water, waste waters and the like.

In the present invention a disintegrating force is allocated to the fluid which may contain the micro-organisms to be detected. If micro-organisms are present, they are broken down at least partially by the disintegrating force and the cell debris and contents cause a change in at least one optical property of the fluid, such as a change in the turbidity of the fluid. This is generated from example release of intracellular matrix or chemicals, rapture of cellular walls, which will spread pieces of non-polar membrane in the liquid. Such effect could be also detected with change of conductivity and/or permittivity of the liquid. By detecting e.g. the turbidity before and after the disintegration, and defining the change in turbidity of the fluid caused by the degradation, the presence and/or quantity of the microorganisms may be defined. The required steps for detecting micro-organisms are shown in the flow diagram 100 of Figure 1. Basically first the optical property, such as turbidity of the fluid is measured in step 102. Next the disintegrating force is allocated to the fluid in step 103. After this in step 104 the turbidity is measured again to define the possible change in turbidity. These basic steps can be repeated plurality of times to obtain more accurate measurements and the disintegrating force may be pulsed as well as the measurement of turbidity, for example by using visible light. This way also the effect of background is decreased.

Use of disintegration force pulses helps to remove effects of dirt accumulation to measurement instrument and eliminate external effects, such as external light and dirt in the liquid to be measured. The purpose of pulsing mode referred here is two fold; a) to have ON and OFF pulsed with standard intervals. Then the measurement can be made during the OFF pulses, using different wavelength. With other configurations additional measurement can be made during the ON phase, if the same as the disintegrating wavelength. b) Using different intervals for ON-pehod, it is possible to estimate the amount and type of micro-organism. For example with exposure times (or similar ra- tios to exposure ratio) of 1 , 2, 4 and 8 seconds, it is possible to estimate the half time (1/2) of micro-organism decay. Mathematical fit can provide sufficient information, although all the micro-organisms were not disintegrated.

It should be noted that according to an embodiment of the invention it is also possible to make the measurements also during the UV-exposure period with or with- out illumination light. According to an example the UV-radiation can be used in addition to the disintegrating force also as an illumination light beam for the detector, whereupon e.g. the scattered UV-radiation beams are measured in order to determine e.g. the change of the turbidity of the fluid.

The measurement instrument can contain a cleaning unit, which will remove dirt accumulation from optical pathways. There methods may include brushing, high pressure and speed flow, chemical washing agent, vibration such as ultrasonica- tion, electric discharge, and electrical current in DC or AC.

The device can also include a UV indicator component, in order to check the UV radiating power of UV-LED, in order to monitor device condition. In the embodi- ment of other than UV disintegration force, other disintegration forces can be advantageously measured respectively.

According to an embodiment of the present invention the fluid referred in this text and patent claims can comprise in addition to liquids also of any gas, able to carry any said micro-organisms. Therefore the presented device can be used to meas- ure also the airborne micro-organism, such as fungi spore or bacteria, created by exhaling or sneezing. It is also possible to get the gaseous substances bubbled into a liquid.

In one embodiment the change in turbidity is detected and defined continuously during the disintegration i.e. the disintegrating force is not turned OFF. In such case the disintegration and the detection of turbidity should not interfere with each other.

The disintegrating force may be for example UV light, electricity, radiation, shock heating or freezing, mechanical force applied by a needle or blade for example, pressure shock or a chemical, such as cytocide, ultrasonic, or ionisating radiation, or any combination of those mentioned. In one advantageous embodiment the disintegrating force is allocated by using a UV light. Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 400 nm to 10 nm, and energies from 3 eV to 124 eV (Wi- kipedia). Generally ultraviolet C ranging from about 280 to 100 nm in wavelength is considered germicidal. In one embodiment the wavelength of the UV light is about 254 nm. This wavelength is known to effect with the DNA, possibly by polymerizing it, and is thus referred in this document also as a disintegrating force as it causes changes in living organisms, such as deactivation. The polymerization causes a change in the optical property of the fluid which can be detected according to the invention.

In one preferred embodiment of the present invention the UV light source is a ultraviolet light emitting diode (UV LED), even though also other UV sources can also be used, such as UV tube. UV LEDs in a range of wavelengths are currently becoming available on the market. One advantage of the use of UV LED is that when compared to the conventional Hg light sources the UV LED can produce the UV light even 100 times more efficiently. Further, the UV LED is very compact and it makes possible to design small devices, such as probes. LED is also a very fast light source which is beneficial e.g. in applications using pulsed light.

In order to define the presence or amount of the micro-organisms in the fluid, the change in the optical property of the fluid, such as turbidity must be measured. Generally the turbidity of fluid is defined by measuring either scattered light or passed light or both. In one embodiment of the present invention the turbidity is measured by providing a light beam from a light source to the fluid and detecting scattered light only. The light emitted by the light source may be broad spectrum light, such as visible light, UV-A, UV-B, or a combination of UV and visible spectrum. Any change in the scattered light due to the disintegrating force advantageously indicates the presence of micro-organisms. Thus, according to an embodiment of the invention the directly transmitted light is not even needed to be measured but any presence of the micro-organisms in the fluid can be determined using only the detector detecting scattered light.

According to an embodiment of the invention also a light polarization change due to the disintegrating force applied into the fluid may be measured. It has been noted that a certain micro-organisms when disintegrated changes the polarization angle detected by the detector. In addition the amount of the change of the polarization angle may be characteristic for the micro-organism, whereupon at least the type of the micro-organism can be determined by the amount of the change in the polarization angle.

According to an another embodiment different angle polarizers may be used be- fore the different detector (e.g. 14a and 14b). The polarizers on the at least one detector may be fixed in an angle with each other so that no light is passed for the "pure" fluid on the other detector. Thus, if the fluid comprises any microorganisms, they will (when any disintegrating force is applied on the fluid) advantageously change the polarization of the illuminating light, whereupon part of the light beams are passed by the polarizer and detected by the detector. At the simplest, if any light is detected by the correctly detector it is an indication of the presence of micro-organisms in the fluid.

The light source used for illuminating the fluid or in other words for measuring may be any suitable light source, such as a LED, a light bulb, fluorescent tube or the like. According to an embodiment as the light beam passes through the fluid it hits the disintegrated parts of the micro-organisms and scatters. Alternatively the broken cell may make the fluid more transparent for used illumination wavelength. Whether the fluid becomes more transparent or turbidity may depend e.g. on the used illumination wavelength, as well as also the particle size of the broken cell, for example. Scattering is a general physical process whereby some forms of radiation, such as light, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass.

In another embodiment of the present invention the turbidity is measured by providing light from a light source to the fluid and detecting absorbed or transmitted light. In still another embodiment both the scattered light and transmitted light are detected.

In one specific embodiment the spectrum of the scattered light and/or the transmitted light is detected. This may help to distinguish different species of micro- organisms from each other as they have their own specific spectrum. The spectrum as used herein is not limited to any specific wavelength range but rather indicates that more than one wavelength is monitored.

The fluid may also flow during the method. This is useful for example in cases where the method is carried out in a flow chamber. Depending on the positions of the means for disintegrating force and the means for detecting the change in turbidity the steps may be carried out as a function of time or as a function of space in the case of flowing fluid.

In addition it should be noticed that the sample to be measured may be concentrated in step 101 a before allocating any disintegrating force to it, advantageously also before measuring the optical property first time. The concentration is advantageous for example if the amount of the micro-organisms in the fluid is minimal, whereupon in step 101 a the concentration of the micro-organisms can be increased and thereby allowing more reliable detection. Alternatively disintegration force can be turned on and off for sequential liquid samples, whereupon the sam- pie which is not allocated by the disintegrating force is as a reference sample.

Moreover it should be noticed that an additive may also be introduced in step 101 b with the sample to be measured before allocating any disintegrating force to it, advantageously also before measuring the optical property first time, so that the additive will react with the micro-organisms, such as binding to the surface of the micro-organisms or penetrating into the inner structure of the micro-organisms. The advantage of the using of additives is that the possible change of the optical property may be much stronger after disintegration than without the additive, whereupon again smaller amount of the micro-organisms can be detected. The additive may be for example a chemical or dye such as acridine orange. According to an embodiment of the invention both the concentrating as well as also introducing an additive may be applied at the same time or for the same measurement.

The present invention also provides a device and arrangement for detecting microorganisms from fluid comprising means for allocating a disintegrating force to the fluid and means for detecting the change in optical property, such as turbidity of the fluid before and after or during the disintegration wherein change in the optical property as the result of the disintegration of the micro-organisms indicates the presence of the micro-organisms. The device may be connected to a central unit which collects and stores the data, processes and analyzes it, or such central unit may be integrated to the device. The device may comprise an optical pathway cleaning unit on any known technology. The device may be arranged to perform any method of the present invention. In addition an embodiment of the invention relates to a computer program product, which can be used for controlling the op- erational steps of the measuring device, such as controlling the flow rate of the fluid in the measuring tube, switching the disintegration force, such as UV light on/off for an appropriate time period, as well as controlling the light source used for emitting a light beam into the fluid to be detected by the light sensitive detectors and collecting the data measured by the said detectors. One embodiment of the present invention is shown in Figure 2. In this embodiment the disintegrating force is a UV led 10 and the means for detecting the scattering light include a light source 12 and a light detector 14. The flow direction is indicated with arrows. When the micro-organisms 16 enter the channel, the UV LED 10 emits strong UV light which disintegrates the cells. The light source 12 emits advantageously light to the channel and the light scattering from the cells or cell debris and the light detector 14 detects the change in light scattering.

Another embodiment of the present invention is shown in Figure 3. The arrangement is the same as above but now the light source 12 comprises a pattern of light units and it is positioned essentially parallel to the flow channel and the light detec- tor 14 is at the other end of the channel. According to an embodiment each of the light unit can be controlled separately, whereupon the light units can be switched on/off synchronously with the flow rate. Thus the development of the disintegration can be monitored along the fluid flow in the channel.

In one embodiment of the present invention shown in Figure 4 the device compris- es an elongated measurement probe 18 arranged to be dipped into fluid, the probe having an aperture 20 accessible to the fluid containing an UV LED 10 for allocating disintegrating force, a light source 12 and a photo detector 14 for detecting scattered light and/or transmitted light. This device is especially advantageous as a compact probe which can be integrated to a hand held central unit (not shown) which may have means for collecting, processing and/or analyzing the gathered information and outputting the results. Figure 5 illustrates another exemplary measuring construction 50 for detecting the presence of micro-organisms in the fluid according to an exemplary embodiment of the present invention, where the construction comprises plurality of UV light sources 10 (like LED), plurality of light sources 12 for emitting light beams used for measuring any change in the optical properties of the fluid flowing in the channel, as well as at least two light sensitive detectors 14. The construction 50 allows the monitoring of the development of the disintegration as a function of time. The first UV LED 10a causes some disintegration and a change to the optical properties of the fluid, which effects can be measured by emitting the first light beam 11 a by the first light source 12a. The directly transmitted light beam 11 ai can be detected by the first detector 14a. However the disintegration of micro-organism causes also scattering, which can be detected from the scattered light beam 11a ₂ by the other light sensitive detectors 14a, 14b, etc.

When the fluid flows in the tube the second UV LED 10b may be applied to allo- cate the disintegrating force to the flowing fluid so that the UV light beam 11 b emitted by the second LED 10b allocates further disintegrating force to the fluid causing further disintegration of the micro-organisms and further changes to the optical properties of the fluid, such as turbidity, which again can be detected by emitting e.g. a second light beam 11 b by the second light source 12b. Again the directly transmitted light beam 11 bi can be detected by the first detector 14b and the scattered light beam 11 b2 by another detector, such as detectors 14a, 14c, etc.

It should be noted that the UV light source may be one elongated UV tube (which may be as long as the measuring portion of the flowing channel) or it can be consisted of plurality of separately controllable UV LEDs as in figure 5. Again it should be noted that the detection of the change in the optical properties and thus also the presence of any micro-organism in the fluid can be implemented by using at least one light source 12 and at least two light sensitive detectors 14. The operation of the light sources 12a, 12b, 12c as well as also the read out of the detectors 14a, 14b, 14c can be synchronized so that they do not disturb each other. For ex- ample the UV light source can be switched off during the measurement, and the light sources 12a, 12b, 12c can be flashed consecutively. The read out of the light sensitive detectors can also be controlled so that they are read out synchronously with a certain light source. According to an embodiment a light beam emitted by one light source can be detected by the all light sensitive detectors, whereupon the change of the optical property may be determined more reliable. Figure 6 illustrates an exemplary concentrator 60 for concentrating possible microorganisms from the fluid before measurement according to an exemplary embodiment of the present invention. The concentrator is advantageously applied in the upstream of the flow so that the concentrator may remove excess of fluid, such as water for example, whereupon the more concentrated fluid (proportional of microorganisms higher than before concentration) with micro-organisms is led for the measuring chamber. Otherwise the measuring arrangement may be similar that disclosed elsewhere in this document.

It should be noticed that the arrangement comprising an additive means for intro- ducing the additive into the fluid may be structurally similar than the arrangement illustrated in figure 6, whereupon the concentrator 60 may be replaced by the additive introducing means. According to another embodiment the arrangement may comprise both the additive introducing means and the concentrator advantageously applied in the upstream of the flow, as the concentrator 60 in figure 6. Figure 7 illustrates an exemplary measuring arrangement 70 having a reference chamber 71 for a reference measurement and the measuring chamber 72 for measuring the possible changes in the optical properties due to disintegrating force according to an exemplary embodiment of the present invention. The arrangement 70 comprises advantageously UV light source 10 (or other means) for allocating disintegrating force into the fluid conducted to the measuring chamber 72. In addition the arrangement 70 comprises at least one measuring light source 12, which may be adapted to emit light beams both to the fluid in the reference measuring chamber 71 (non-disintegrated) and to the fluid in the measuring chamber 72 (disintegrated). Thus the optical property, such as absorption or tur- bidity, can be measured similarly from the original fluid and the fluid exposed to the disintegrating force, whereupon the effects of the allocated disintegrating force can be more reliably determined. The optical property determined from the fluid in the reference chamber 71 is advantageously the same as determined from the fluid in the measuring chamber 72, whereupon the determined values are compa- rable with each other.

Figures 8A - 8C illustrate an exemplary measuring arrangement 80 for measuring a change of an optical property, such as turbidity or absorptivity, according to an exemplary embodiment of the present invention. The measuring construction comprises a cuvette 81 having the fluid with the micro-organisms to be detected. In figure 8A the first light beam is emitted by the measuring light source 12 and a certain optical property is measured, such as turbidity. Since the micro-organisms are not disintegrated yet, light beams scattered from the micro-organisms are detected by the second detector 14b. Also reference light beams may be transmitted essentially directly to the first detector 14a. In figure 8B the disintegrating force is applied, i.e. in this embodiment the UV light source is switched ON. The exposure time of the UV light depends on e.g. the intensity of the UV light as well as the spectrum, but varies typically from seconds to minutes.

As can be seen in figure 8B the micro-organisms will be disintegrated due to UV light. After exposure the same optical property, here the turbidity, as measured in figure 8A is measured again in figure 8C for detecting any change in said optical property and thereby having some indication of the presence of the microorganisms in the fluid. Now the disintegrated micro-organisms will make the fluid more transparent for the used wavelength of the light beams of the measuring light source 12, whereupon less scattering of the light on the detector 14b and more the emitted light beams are detected by the first detector 14a. According to an embo- diment of the invention the presence and also in some ideal cases of clean sample the type of micro-organism could be indicated from the ratio of scattered and transmitted light detected by the detectors 14b and 14a, respectively.

It should be noticed that for some other type of micro-organisms or by a different wavelength of the illumination light beams the disintegrated micro-organisms may cause more scattering than the micro-organisms which are not yet disintegrated. However, there is also the change in the optical property, namely in turbidity, due to the disintegration force, which is detected and which change indicated the presence of the micro-organisms in the fluid.

Figure 9 illustrates another exemplary measuring construction 90 for measuring a change of an optical property, namely reflectivity, according to an exemplary embodiment of the present invention, where the fluid is either in stationary state or flows slowly (there is no matter of the flow direction 92) in the measuring chamber 91 during the measurement. The measuring construction 90 comprises disintegration force unit, which is now an UV-radiation tube 10, a measuring light source for emitting light beams into the fluid and at least the second light sensitive detector 14b. The second light sensitive detector 14b may comprise light guiding means, such as a prism or lens for collecting scattered light beams from the measuring chamber 91.

In the measurement part of the light beams emitted by the light source 12 may be transmitted directly through the fluid into the first detector 14a, whereas part of the light beams emitted by the light source 12 may be scattered either by the microorganisms or disintegrated micro-organisms in the fluid. The light beams scattered in a certain angle reflect from the inner surface of the measuring chamber (similarly as in an optical fibers) and finally reaches the end 91 a of the tubular chamber. Now, when the end 91 a has a certain shape, such as a certain angle α, the light beams advantageously refract so that they can be collected e.g. by the guiding means into to the second detector 14b. In addition, according to an embodiment of the invention also a mirror 93 can be adapted into the second end 91 b of the tubular chamber in order to guide the scattered and reflected beams back towards the first end 91 a of the tubular chamber and thereby strengthen the detected signals by the second detector 14b.

Tube 91 can also be more tube shape, which any angle alpha, preferably 90°. In this case the outer edges of the tube may be used to collect the refracted turbidity light, or reflect it to the other.

Now, if the fluid comprises micro-organisms, the applied disintegrated force will disintegrate the micro-organisms, which causes a change in the scattered light beams and which change can be detected by the second detector 14b. In addition the first detector 14a can also be used for analyzing directly transmitted light beams and thereby more reliable results can be achieved, even though the pres- ence of the micro-organisms in the fluid can be detected also by only using the second detector 14b.

Figure 10 illustrates an exemplary embodiment for calculating out effects of sample inhomogeneity and dirt accumulation according to an exemplary embodiment of the present invention. Illumination light from the light source 12a or 12b is in the figure divided to two light I ₁ and h, which are pulsing on, one at the time. The reference sensor 14a or 14b is also divided to two, which are aligned so that they are receiving equal amount of light from illumination source 12a or 12b. When the illumination light source light is switched, the effect of sample inhomogeneity and dirt accumulation, agglomeration can calculated out.

Figure 11A illustrates an exemplary behavior of concentration of micro-organisms during the allocation of disintegrating force (here UV radiation) into the fluid including micro-organisms [Photoreactivation and Dark Repair in UV-Treated Microorganisms: Effect of Temperature; I. Salcedo, J. A. Andrade, J. M. Quiroga, and E. Nebot; APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Mar. 2007, p. 1594- 1600]. It is known from the prior art, that micro-organisms inactivate due to UV exposure, but they can also reactivate after a certain time in a certain circumstances, such as in a certain temperature. The figure 11A shows an exemplary in- activation-reactivation curve of micro-organisms as a function of time during the allocation of UV radiation, where N ₀ is the concentration of micro-organisms before UV radiation, N _d is that after disinfection caused by the UV-radiation but before reactivation, and N ₁ - is that at time t after the beginning of the reactivation phase. N _m is the maximum concentration of micro-organisms reached by reactivation.

Figure 11 B illustrates an exemplary measuring data related to the turbidity of the fluid having micro-organisms and exposed by UV radiation. The change in the tur- bidity can be clearly seen already from the beginning of the UV exposure, where the change indicates the presence of the micro-organisms. The reactivation of the micro-organisms increases again the amount and thereby the concentration of the micro-organisms in the fluid (as can be seen in figure 11A), which in turn induces a further change to the optical property, such as turbidity, of the fluid, which can be seen in the figure 11 B (the growing part of the curve after 25 min). Thus the further change can be used as a further indication (confirmation) of the presence of the micro-organisms in the fluid.

In addition, it is known that e.g. DNA, RNA and nucleic acids absorb a certain wavelength. For example nucleic acids absorb both 260nm and 280nm, whereas pro- teins absorb essentially only 280nm, whereupon the purity of the nucleic acids can be detected from these absorption peaks. In addition according to an embodiment of the invention the existence of this absorption and especially the absorption in 280nm (caused by proteins, the amount of which is increased due to disintegrating force, such as UV-radiation, applied into the fluid) can be used also as further indi- cation of the presence of the micro-organisms in the fluid. For example when the change in turbidity is detected due to disintegration of the micro-organisms, a light beam from the measuring light source with another wavelength can be emitted to the fluid and if there are disintegrated micro-organisms (and thereby DNA / RNA sequences or nucleic acids in the fluid) they will absorb a certain wavelength, which can be detected by the detector sensitive for said wavelength.

Furthermore even a further indication of the presence of the micro-organisms in the fluid can be achieved by an embodiment of the invention, where a fluid with micro-organisms is exposed by UV radiation and e.g. a change of turbidity is detected, namely detecting also a possible emission. It has been detected that during the UV exposure there exists an emission at the wavelength of 550.5 nm the intensity of which changes highly especially at the beginning of the UV exposure, such as during the first 5 minutes. The wavelength relates to a cytochrome-c- protein, which exists inside the micro-organisms, like cell. Thus, if there are microorganisms in the fluid and they are disintegrated e.g. by UV radiation, the inner structures of the micro-organisms, such as the cytochrome-c-protein, will be exist in the fluid as such (outside of the cell), and when the fluid is then exposed by a certain exciting wavelength (e.g. either UV radiation having λ < 400 nm or using a LED having λ < 265 nm, which is a certain excitation wavelength) the protein e.g may excite and the emit a light beam with a wavelength of 550,5 nm. It should be noticed that the wavelength of 550,5 nm is characteristic for a certain cytochrome- c-protein, but the other proteins or inner structures of the micro-organisms may have another emission wavelength.

The invention has been explained above with reference to the aforementioned embodiments, and several advantages of the invention have been demonstrated. It is clear that the invention is not only restricted to these embodiments, but com- prises all possible embodiments within the spirit and scope of the inventive thought and the following patent claims.

Especially it should be noticed that a device according to an embodiment of the invention can comprise illumination light A (12) (such as 400 nm or visible light), reference sensor B (14a), which is essentially planned to measure the transmit- tance, C (14b) scattering detector which essentially measures the turbidity, and D (10) the disintegrating force, such as UV-radiation source. Furthermore in some embodiments the B may have more than one wavelength. Again the B and C may be the same physical component in the devices illustrated in the above Figures, alternative to measuring only B. Separating the optical signal for B and C may be achieved with collimated light to B or by using polarization.

Still it should be noted that a part of micro-organism (such as proteins) may have fluorescent properties, which can be detected or measured when exposed e.g. by the UV-radiation. For example, when the fluid comprising this kind of microorganisms, are exposed by the UV-radiation of 400nm, it may emit some fluores- cent radiation with a longer wavelength than the wavelength of the UV-radiation used for exposing. Alternatively a fluorescent marker may be added (for example in connection with step 101 b), which will bind directly or via a specific chemical to the micro-organism or part of it (such as protein), which quantity or at least optical property, such as fluorescent emission, will clearly change during the UV- exposure. In principle the fluorescent marker does not cause any fluorescent emission if there are no particles, such as parts of micro-organisms in the fluid, to which the marker can bind.

Moreover it should be noticed that in one embodiment of invention illumination light sources 12 in the above Figures may be realized with a UV-radiation source 10, which optical signal (such as wavelength) may be filtered, whereupon the detectors 14 is adapted to detect possible changes in the optical property of the fluid by measuring at least one component of the UV-radiation.

In addition it should be noted that even though the concentrator 60 is depicted only in connection with the Figure 6, the concentrator 60 can also be applied for other devices depicted in other Figures, such as especially in the devices illustrated in the Figures 2, 3, 5 and 7, for concentrating possible micro-organisms from the fluid before measurement. Moreover in the arrangement 70 shown in Figure 7 a filter may be applied so (not shown) that the possible micro-organisms are not reached into the reference chamber 71 but only into the measuring chamber 72.

Furthermore the invention relates also to a computer program product for detecting micro-organisms from fluid, where the computer program product is at least adapted to control (when run at a data processing means, such as a computer) an allocating of at least one disintegrating force to the fluid, where said force is capable of disintegrating the micro-organisms in the fluid, and detect a change in at least one optical property of the fluid by controlling of a measurement of the optical property before and after or during the disintegration.

The controlling of the allocation of at least one disintegrating force may be for example controlling the parameters of the UV-radiation source, such as its power. In addition the detecting may comprise for example controlling the parameters and operation of measuring light source, such as switch the measuring light source 12 on and off and the power of light source and possible synchronization of plurality of light sources, as well as also gathering the measurement data from the light detectors 14a, 14b. The computer program product may also be applied to control the angle of the polarizers.

In addition the computer program product is adapted to indicate the presence of the micro-organisms based on the change in at least one optical property as the result of the disintegration of the micro-organisms, such as based on the change in the scattered light measured by the detectors and analyzed by the computer program product.